Common-battery two-wire repeater system.



i UNITED STATES NPATENT oFFIoE.

TALBOT G. MARTIN, OF CHICAGO, ILLINOIS, ASSIGNUB T AUTOMATIC ELECTRIC OOMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

OOMMONBATTERY TWO-WIRE REPEfTER SYSTEM.

To all whom it 'may concern.'

y Be it known that l, T'ALBoT G. MARTIN, a citizen of the United States oi America, und resident of Chicago, vCook county, Illinois,

have invented a certain new and useful Imirovement in Common-Battery Two- Wire epeeter Systems, of which the followlng is Y which the said repentcrnnd devicenre each controlled over the two sides ofv thc line in series, as is usual in two-wire systems. In

e system of this kind suitable provision is mede for obtaining connection with the repeuter2 and the lutter is then employed for 'repeating the culling impulses to the nutor:notie switchingdevice for the purpose of causing the letter to seize the celled line, or for. causing the same Vto extend the connection in. the diretion of the called subscriber, depending upon they size and character of the exchange; As's'tnted though, the seid repeater and automatic Switch are both c011- trolled over the 'two sides ofthe line circuit in series, whereby no operating grounds are necessary :it` the substntions of the system, or at any other points fromlivhich. it is de# sired to exercise control ci the repeuters und automatic switches.

Myy invention contemplates n system .of

,this kind in which the current oni'iolliingV purposes is suppliedto the substnti'one from s. central source, orjrom suitablemeans prop f vided at the exchange' or central stationfas" 40 distin ishcd from systems in which the .subscrlbers transmitters are supplied with current from local batteries.' For this purpose I provide en 'improved repeater which 1s not onl' 46 the two es oft 4which is in turn" ede ted to control one or more' automatic switc es over the two sides of the trunk circuit inem-ies, but' which is 'e line circuit in series, and

also adapted for usey in w common battery' trunking 'connection between calling and 1celled subscribers. j In this' way certain coils of the Vrepeater may be utilized for feeding talking eurlentto. the calling subscriber in a sy tern in whichno operating grounds are Eli necessary at the substatious,

` Specication of Letters Patent;

Application led July 12, 1909. Berici No. 507,210.

`seen that the switches 1n Fig; 1 are located number of first selectors.4

admired rto be controlled l over" V"with one thousand all Patented Mar. 26,1918.

t The nature and advantages of my invention `V`Will, however, hereinafter more fully appear.

In the accompanying drawings Figures l and 2 taken together represent diagrammetically a, calling substation A connected by means of centraloiice switching appa.- ratus with aV called substation A2 in a, systern embodying the principles of my inven tion. The swltches through which the ste* tions A and A2 are shown' connected com-` prise the socnlled line switch C which is.' allotted to the calling line, the first selector DQEhrepenter R, the second selector E,the connector F andthe line switch C of the called line. `The line switch G is individual to the line 'of the substationApwhile the line switch C4 is individuel to the line; of the substation A. The 'said line switches ere identical.y For o ereting theswitches there is usually provi ed at eeoh'central offices. source of current/or` battery B having its positive terminal referubly grounded 4et l G.M 'By referring to igs. 1 and 2 it will be in -oneroiicfu While ,the switchesv in Fig. ere located at a distant office. The switches in Fig. 2 are operated from substation .A through the 4medium of the. repeater R,

which is allotted tolone of the trunklines connectinthe two exchanges.

It will e understood, of course, that in this system the line switches in each ex- Thereflnny be one-tenthas many offsecond selectors may be one-tenth of the total number 'of subscribers, as well as the A common arrangement isto divide the subscribers into divisions, according to the numbers thereof, the subscribers having numbers beginning p elongng toone division, the subscribers having. numbers be ih` 100 ning With-two thousand belongingto unot er division, and so on throughout. the entire Iten thousand 4subscribers of `the one exchange. This will,- of course, result in ten divisions of any `exchan ehaving a. capacity 106 often thousand subscr-i rs, so4 that in cellinf; `:any subscriber first se ect one of the--teudivisions'i Euch `of these divisions is then subdivided into teny Y groupsthat is to say, the subscribers of il@ any one division, the numbers of which are between one hundred and two hundred, are arranged in one subdivision or group, those between two and three hundred in another subdivision, and so on, the last group being the naught hundred. In this way a ten thousand subscriber exchange is divided into ten divisions, and each division lis then subdivided into ten subdivisions or groups. All of* the subscribers whose numbers are bef tween one hundred and two hundred of any thousand are arranged in a row or larger group; all subscribers whose numbers are between two hundred and three hundred are found in another row or group of subdivisions, and so on' throughout the exchange. With this arrangement any given bank level of any particular subdivision or 'group of rst selectors, which rst selectors represent one hundred subscribers, has connected to it an equal number of second selectors. In a similar manner each bank in any particular group of second selectors has allotted to it a group of connectors, which connectors are adapted to close connection directly with the lines of the called subscribers. Between the first selectors and the calling subscribers are placed the line switches, one for each line, which are arranged in groups or subdivisions. Trunk linesfrom the line switches to the first selectors are provided on the wellknown percentage basis. Also, trunk lines between the first and second selectors and between the second selectors and connectors are provided on the percentage basis, so that ordinarily the trunk lines are less in number than the total number of subscribers. Each trunk line will, then, have multiple ter minals.

The substations in the system may be of any suitable or approved type. The substation A, for example, comprises a receiver 2, a switch hook 3 for controlling the substation circuits, which is accomplished by any suitable means, such as the cam arm 4.

When the switch hook is down the cam arm Y 4 forces the spring 5 into engagement with the spring 6, thereby bridging the condenser 7 and the ringer 8 in series across the line. When the switch hook descends it forces the spring 5 out of engagement with the spring 9', thus removing the primary circuit of the substation from across the line. The primary oircuit comprises the transmitter 10, the primary winding 11 of the induction coil 12, and the impulse springs 13 and 14, all in series. Being an automatic substation it is provided with a calling device includ ing a dial (not shown), an impulse wheel 15 and the impulse springs 13 and 14. The dial is rigidly secured to the impulse wheel 15 and is of the well-known type, provided with linger holes; and when the dial is rotated on returning to normal position the impulse wheel is moved in such a manner as to carry the spring 14 out of enga ement with the spring 13 momentaril as t e teeth 16 come into contact with the ushing 17. It will be understood, o1 course, that the wheel 15 and dial are provided with a proper tension spring which will restore them to normal position on releaes of the dial by the subscriber. Another spring is provided to raise the switch hook 3 when the weight of the receiver 2 has been removed.

The line switch C may be of any suitable or approved type. For example, 1t may be a modified form of the line switch disclosed in British Patent No. 26,301 of 1906, and described in the American T elepone J ouf/"nal of Chicago, Illinois, of June 6, 1908. In its general form it comprises a trip ma net 18 (Fig. l), a release magnet 19 and a4 ridgecut-oii relay 20. The trip magnet 18 is dcsigned to' operate the usual plunger for pressing the bank springs 21 and 22, 23 and 2st, 25 and 26, and 27 and. 28 into engagement. This plunger is so arranged that when. in ndi-mal position it is under the control of the master switch H, whereby the said plunger may always be removed from opposite a busy trunk to a position opposite an idle trunk. The release'magnet 19 operates to restore the plunger to normal position. The bridge-cutoff relay Y20 operates to shift the springs 117 and 114 out of engagement with the springs 118 and 113.

The master switch Il. may be of any snitable or approved type. For example, it may be a modified forni of the master switch described in saidglme'rcmt Telephone J ouf/nal of Chicago, Illinois, of .l une (S, 1908. It comprises in its general form a motor magnet 29, a motor magnet relay 30, a relay 33, ratchet wheel 3G, intcrrupter wheel 37, master switch bank O, `wiper 35 and condenser The master switch shaft controls the plungcrs ot several idle line switches, usuallyr one hundred, always holding them in readiness to engage an idle trunk. This particular master switch shaft has a step-by-step reciprocating motion, and all idle pluiigersare held in locking engagement with said shaft. The plung irs loi the line switches used. in this invention, and as described in the above-mentioned publication, are not self alining-that is, a plunger docs .not automatically come into locked engagement with thc shaft after being tripped, but waits until the shaft again resumes thc original position where the plunger was tripped. W hun cnc line switch operates, its plunger is tripped and engages the springs ol the bank terminals oi' au idlc trunk. The motor magnet relay 30 is accordingly (nicrgizcd, This relay operates to close the motor magnet circuit and open the main relay circuit. The motor magnet 29 operates to rotate the ratchet wheel 36 and interi-opter wheel 37. When the ratchet wheel is rotated one notch the interruptor wheel has moved enough to close the springsy 34, which keeps the motorl magnet operating until the idle plungers are directly op osite the bank terminals of an idle trunk. en thisposition is reached the s rin 34 sepa` rate, and as 'the master. switc `W1 er 3 5 has been moved to a. position on e master 'switch bank corresponding t the terminals of said idle trunk, the motor magnet relay is denergized, which in turn denergizes the motor Ymagnet 29. While the motor magnet is operating, the slovv` acting relay 33 isener` gized, thereby shifting the spring 119 out oi' engagement with the spring 120 and into engagement with theV springI 229; By this operation the trip 'magnets 18 of all of the line switches which 'are controlled by the master switch H are `disconnected from the battery lead, and connected with a busy sig nalin apparatus es long as the said `master switc is operating. This` irevents any line Switch from being operate while the plum 4ger is being moved from one trunk to en other, end "finy subscriber Whoattempts to maken ,call vWhile the master .Snitch .is `openn ating will receive a busy'signal, because his line is connected to a buey' signaling'apparatus through the trip magnet 18 undfsprings 119 and 229.

The first selector switch D may he of' any suitable or approved typefor example, oi'

lthe general type disclosed lin United States Letters Patent No. 815,321, granted March 13, 1906, to Keith, Erickson and Erickson, adapted, however, to a two Wire common battery system. In its modilied'iforrn it coniprises the shaft (not shown) which carries the line Wipers 38 and 39 and `private wiper 40, a side switch whichis Well known and comprises the side switch wipers 41, 42, 43 and 44. The side switch is controlled by the private magnet, and when the side switch is' in first position the side switch Wipers 4l., 42, 43 and 44 engage the contact points 45, 46, 47 and 48, respectively. When in second position, the wipers engage. the contact points 49, 50, 51 and-52,. respectively, and in third position the contact points 53, 54, 55 and 56, respectively. Througlifthe medium o the double woundline4 relay 57, and While the side switch is in first position, the subscriber lcontrols the'vertical magnet 58, which letter operates to reise the switch shaft and shaft wipers 38, 39 and 40 vertically. When the-7- `position the relay 57 is disconnected, it is com trolled Vfrom the next apparatus, which in this case is thc repeater R. YThe private magnet relay 63, being a slow 'acting relay and in series with the vertical magnet, conn trois the private magnet 65, locking the side switch' in its first position While the imp-u lses are being delivered. When the side switch passes to its second position and engages its second position contacts, the'rotery magnet 64 rotates the shaft and shaft Wipers, and when an idle line is found the si e switch is permitted to take its thirdV position.l The release magnet 66 operates to restoreythe shaft and'side switch to their normal posi tion the circuit beingclosed only when the shaft is oil' norma'l and the release rela 62 is in norm'al position. The magnet is 0. the connector-release magnet type. The slow acting relay 31 is connected in the release trunk. kItf'gives the releasemagnet 19 time to release the line switch by holding the trunk open for en instant.

The repeater R shown in Fig. 1 comprises, among other features, the ollowing de'- t-.iils :TA double Wound line rela 67 yhaving the same general features as the v et selector double Wound line rela 57. The relay 67, when operated, forces t 1e springs 68 and 70 into engagement with the springs 6.9 and '71, respectively, energizing the repeater release. relay 72, which is of the saine general type of relay asthe lirst selectonrelease relay 62. 4When the springs 70 and 71 are in contact,

the trunk conductors nre closed through the impedance coil 73.` Y Thus, every time the relay 67is denergized by the opening of the substation cifrcuit, the trunk circuit through the relay springs and impedance coil 73 is broken. The release relay 72 protects the seized trunk by establishing a guarding potential at the private henk multiple contacts and provides a holding ground for the first selector release relay 62. The condensers 227 and 228 are provided to separate the repeater circuits. l

The second selector E (Fig. 2) issimilar to the first selector D, and is provided with the, usual double Wound line relay 74 having its windings 75 and 76 connected to the` trunk line conductors throughr 4the first po' in the usual manner. Sincelik'e arts are similarly represented, the vertice magnet 77, rotary magnet 78, `private magnet 79, privato magnet relay 80.and release relay 81 will be recognized and understood. The release magnet 82 is operated in the same manner4 in connection with the switch, E as the with the switch D. In the switch E the relays 80 and 81 are so arranged that they deenergize slowly, the same as the relays 62 and 63 in the selector switch D. ,y

The connector sWitchF is a modified form of the connector switch disclosed'i-n United States Letters Patent No. 815,176, granted March 13, 1906, to Keith, lErickson and Erickson. The connector switch shaft (not shown), like the selector switch shaft. carrelense magnet (i6 is operated in connection.

ries the line wipers 83 and 84 and the pri vate wiper 85. The connector switch is also controlled by the calling subscriber' through the medium of a double-wound line relay 86 provided with the windings 87 and .88. One terminal of the winding 88 is connected to the battery lead 89, While the other terminal is connected with one trunk line conductor. The winding 87 is connected with ground at one terminal and with the other Vtrunk line conductor at the other terminal. Through the medium of this relay the subscriber con trols the vertical motion of the shaft and Vshaft wipers 83, 84 and 85, by means of thc vertical magmet 90, while the Side switch is in first position; and the subscriber controls the rotary motion of the shaft and shaft Wipers by means of the rotary magnet 91 while the side switch is in second position.

The connector switch F is also provided' i other selector' .from seizing this connector and to provide aholding ground for the release relay 81. of the selector E. The private magnet relay 100, as usual, controlsihe private magnet 101, which latter controls the side switch wipers. The back-bridge relay 95, comprising the windings 96 and 97, serves. as a means whereby the called subscriber is provided with battery current for talking purposes.

As illustrated, the connector switch is of the automatic ringing type-that is, a sig naling of the called subscriber is4 not dependent upon the calling subscriber pressing a signaling button, for as soon as connection is established with the called line, the in terrupter 98 intermittently closes an ener gizing circuit through the ringer relay 99, whereby the terminals of the ringer generator I are intermittently 'bridged across the normal conductors of the called line. The busy locking relay 102 is so arranged that if a busy line is called the connector side switch is locked in second position and the calling subscriber is given the busy signal. The means whereby the connector switch is released consists of the usual connector re; lease magnet 103 which, when the switch shaft is raised 4one or. more s teps, is connected to the battery lead 89 by the normal spring 104 and contact point 10.5. By means of the condensers 106 and 107 the circuit through the connector is divided into two sections. The busy signaling apparatus J comprises the interruptor 108 in series with the winding 109 of the induction coil 110. The winding 111 is connected with the spring 112 of the private magnet 101.

The operation of the system may be more clearly understood from an explanation of its operation in the course of establishing a connection. It is assumed that the subscriber at substation A wishes to call the subscriber at substation A2, which islike substation A. and desi nated as` number 2220. The-operation oA the central oiiicev switches to bring about this connection is as follows: When the subscriber at substation A removes the receiver 2 from the switch hook the cam arm 4 allows the springs 5 and 9 to engage, whereb f an energizing circuit is completed for t 1e trip magnet 1.8, said circuit extending :trom ground G through the bridge-cutoff relay springs 11.8 and 117, line conductor 116, switch hook springs 5 and i?` impulse springs 13 and 14, primary win-:bug 11 of the induction coil 12, transmi; fr .10 of substation A, line conductor 115,.y bridge-cut-of relay springs 114 and 113, trip magnet 18, relay springs 119 and 124i tobattcry lead 89, thence through battery B to ground Gr. As soon asithe trip magnet 18 energizes, the plunger arm is tripped and the plunger engages the bank springs previouslyv mentioned. W'hen the bank springs of an idle trunk are thus closed the line conductors 115 and 116 are cut through to the trunk line conductors 122 and 123, whereby the line relay 57` of the .first selector D' is enerlglized. This circuit extends from ground 5 through the winding 132 of the relay 57, contact point 46, side switch wiper 42, trunk line conductor 123, springs 28 and 27, line conductor 113,'` primary circuit of substation A, line conductor 115, springs 21 and 22, trunk line conductor 122, side switch wiper 41, contact point 45, winding 133 to the battery lead 89, thence through battery B to ground G. The relay 57, upon energizing, operates to disengage 'the spring 135 from the spring 131i and to place the springs 135 and 136 in contact. lThe former action clears the release trunk 131 of the ground G", which prevents the release magnet 19 of the line switch from energizing. The

"latter action establishes an energizing circuit through the release relay 62, said circuit extending' from ground G throughq the springs 135 and 136, release relay V62 to the battery lead 89. The release relay 62, upon energizing, operates to carry the spring 137 out of engagement with the `138 and into engagement with the sp ng 39. This is the condition of the first selector D whenV the subscriber operates the dial for the first digit. close, as the line switchlgpllnger trips, the bridge-cutoff relay 20 is energized over a. circuit extending from ground Gra through said bank 4 springs, bridge-cutol relay 20 to the battery lead. The relay, operates,V forcing the springs 114 and 117 out of engagement with the springs 113 and 118, clearing the line conductors 0f the line W'hen the bank springs 25 and 26' res conductors 143 switch Wiper 44- to the battery lead 89, thence through battery B to ground G. The said rotary magnet then operates to rotate the shaft and shaft engzwen'ient with the lil-.st contact of the sccond lavel of the selector banks, from which contact it is assumed the trunk conductors 143, 144 and 145 lead to the repeater R. If the first trunk line is busy, however, and the wipers have to pass over busy trunlelines, then as soon as the private wiper 40 engages the first private bank contact the private magnet again energizes, locking the side switch in second position. The energizing circuit for said private magnet extends from the grounded terminal G'ot the battery B through a busy repeater R (not shown) through the private wiper 40, side switch wiper 43, contact point 51, private magnet 65 to battery lead 8f), thence through battery B to ground G. The rotary magnet 64 will then emitinue to rotate the shaft Wipers 38, 39 and 40 until the private wiper 40 leaves the last busy contact and the energizing circuit of the private magnet 65 is broken, denergizing the private n'iagnet and permittin the side switch wipers to engage their t iird position contacts. The energizing circuit o' the rotary magnet 64, as Well as the energizing circuit of the line relay 57, is broken when the side switch takes the thi position bu triuilt-lines the side switch is tripped to third position. as soon as the wipers are carried into engagement with the first trunk line. As soon as the side switch passes to third position, as stated, the subscribers line conductors 115 and 116 are extended to the and 144 which, in this case, it is assumed lead to the repeater R, and when thus extended an venergizing circuit iS established through the line relay G7 of the repeater switch. Thisl circuit extends from ground G7 through one winding of the line relay 67, conductor 144, shaft wiper 39, contact point 54. side switch wiper 42, trunk-line conductor 123, bank springs 28 and 27, line conductor 116, primary circuit of substation A, line conductor 115, bank springs 21 and 22, trunk-line conductor 122, side switch Wi er 41, contact point 53, shaft Wiper 38, con uctor 143, through the other winding of the line relay 67 to the battery lead 89, and through battery B to ground G. The line relay, upon energizing, forces the springs 68 and 70 into engagement with springs 69 and 71, respectively. The springe 68 and 69, on thus being closed, set up an energizing circuit for the release relay 72 from ground Grs through the syn'ings 68 and 69, release relay en said relay operates, the sljiring 146 engages the spring 147, providing an energizing circuitfor the release relay 62 of the selector D and establishing a guarding powipers 38, 3i) and 40 into lf, however, there are no 72 to the battery lead 89.'

tential at the corresponding private Contact of the other selector banks to prevent anol her selector' from seizing this trunk and repeater. Said energizing circuit extends from ground G" through the springs 147 and 146, conductor 145, shaft wiper 40, side switch wiper 43, contact point 55, release relay 62 to the battery lead 89, thence through battery B to ground G. Thus the selector l) prevented from releasing by means of the ground at` the repeater R. When the line relay springs 70 and 71 close in contact, an energizin circuitl is established for the line relay 74 (Fig. 2) of the second selector E over the trunleli'ne conductors 148 and 149. This circuit extends from ground G1 through the winding 76 of the line relay 74, side switch contact point 150, side switch wiper 151, trunk line conductor 149, resistance coil 73 of the repeater R, springs 71 and 70, trunk-line conductor 148, side switch wiperi152, contact point 153, winding of the linb relay to the battery lead 89, thence through battery B to ground G. The relay 74, upon energizing, operates to place the springs 154 and 155 1n contact, and to disengage the spring 154 from the spring 15G, whereby an energizing circuit is established through the release relay 81, said circuit extending from ground G12 through the springs 154 and 155 release relay 81 to the battery lead 89. lhe relay 81, upon energizing, operates to carry the spring 157 out of engagement with the spring 158 and into engagement with the spring 159. This is the condition of the second selector and repeater when the subscriber operates the dial for the second digit. It is seen that the trunk line between the first and second selectors is divided into two sections by the condensers 227 and 228, and that all selective impulses delivered to the second selector and connector at the distant exchange are transmitted through the repeater R. i

The second digit being 2, the impulse' spring 14 is'twicc carried out of engagement with the impulse sprin q13, whereby the energizing circuit throug the repeater line relay 67 is twice broken momentarily. The relay 67, of course, denergizes twice momentarily, and permits the springs 70 and 71 to disengage `twice for a short period of time, thus breaking the energizing circuit of the second selector line relay 74 twice. When the impulses are transmitted both line relays are operated over the same circuit as previously traced.' The release `re lays 72 and 81, being slow-acting as mentioned, do not denergize during the transmission of the impulses, but remain in an operated condition. When the relay 74 decnergizes momentarily the spring 154 engages the spring 156, whereby an energizing circuit is completed through the vertical magnet 77, said circuit extending from switch circuit. When the bank springs23 and 24 lare closed in contact, an energizing 'circuit is established through the motor magnet" relay 30, it being understood that the ground connection to the release trunk at the selector' D is removed almost 1nstantaneously. Said energizing circuit extends vfrom ground Gr through relay 30, common vsie,g,fmeii'.t-124= of the master switch bank O,

circuit; but the owirof current is no t sufficient to` operate the `magnet though the ref;

lariis opwaardering ,the raptor magnet circuit an thezcircuit. of the `relay 33. lhe niotormagiintcircuitsoxtenda Pfromv` ground Gt through the magnet 29, interruptor springs 121, motor magnet -ielay springs 125 to the batteryl leadthence through battery B to round G. The circuit of the relay 33 extends from ground- G2 through the relay 33, interruptor springs '121, motor magnet relay springsv 125 to'the battery lead. The

relay 33 is sloii'factiIig--that is, slow to `deenergi'ze, and thus remains in an operated condition while the motor` magnet is operatingto Iadvance the ratchet wheel 36 and interrupter.. wheel 37, which in turn advances all idle. lingers that are in locking engagement with the shaft to a position opposite the next idle bank terminal. The relay 33, when operated, disconnects the battery lead- `from all trip magnets, thus making it irripossiblefora trip" magnet to release a: plan `r .While the motor magnet is operati-ng, hen the wi er 35 leaves the individual contact 12?,'an ifthe next individualcontact-is not guarded by a battery potential, the motor relay 30vwil1 be dciiergzed. However, the motor ma net will continue operating the `ratchet w ieel until the idle plunger's are in a position. difl idle trunki rcctly in front ofthe waiting This is accomplished b ythe springs 34, which are arranged in mult le with the springs 125,1nakingacontact until forced apart by the interruptor wlieel?. It is evident that in order to give Athis condition the interruptor wheel 3.7 inustfbe set ina position to oper* atc these springs 3ft according to the relative position of the iille plunger-s. It will be understood that the bank terminal (shown) of the `line switch bank corresponds to the first segment of the master switch bank O` and, therefore, corresponds to the. trunk line conductors 122, 123 and 131 which terminatcin the selector'. D. The engagement of the bank springs 25 and 26,'besid'es providin an, energizing circuit for the bridge-cuto-iig relay, establishes ai guarding potential over the private normal conductor 130 to the connector bank terminals corresponding to the li ne of the calling subscriber, to prevent any other subsci'ibci from calling the said line after the calling subscriber at substation A removes his receiver preparatory to making a call. Up to this point the subscriber at substation A has simply removed his receiver. He now turns the dial for the .first digit of the number desired, releasing it when it returns to normal position. f The first digit being 2, the impulse spring 14C is twice carried out of engagement wit the impulse spring 13, whereby the energizing circuit through the line relay 57 is broken twice, and the spring 135 cornes into contact with the spring 134 twice. After the two impulses are thus delivered, the line relay again euergizes and carries the ,spring 135 into contact with thespring 136. A s previously explained, the relay 62 is a slowacting relay-that is, slow to denergize; and when this energizing circuit is momentarily broken, during the im ulses just devertical magnet is thereby energized twice 100 and the shaft and shaft wi ers raised two vertical steps inthe wellown manner. It will be seen that the private magnet relay (i3-is also included in the energizing circuit of the vertical magnet 58. energizes, but being a slow acting r ay it operates on the first impulse and `remains, in an operated position until all the impulses are delivered. This relay, upon energizing,

This rela also operatesv to close the springs leidend 11M in` 110 contact, whereby an energizing circuitl is established. through the private magnet 65, said circuit ciitendin from ground G through springs 140 au 141 private magnet 65 to thebattery lead 89. 'Illa net relay 63 denergizes after the last pulse, since this energizing lcircuit is no longer maintained after Vthe springs 134i and 135 disengage. `Hence said relay permits by the energizing circuit through the private magnet 65A is broken, which private magnet dener 4'zes and` permits the side switch wipers 4 4anda-ll: Vto engage the contact points 51 and 52, respectively. sure of contact between .the side switch wiper Y 44 and contact pointA 52 sets iup' an energizing circuit for the rotary magnet 64 from ground `G through the interrupter springs e private magthe springs 140 andlil to disengage, where 120 The clo- 149 rotary magnet 64. contact point 52, side 130 l guarding potential for ground G1 through the springs 151 and 156, springs 157 and 159, private` magnet re lay 80, vertical magnet 77, Contact point 160 side switch wiper 1.6.1 to the battery 89. The vertical magnet 77 is thereby and the shaft and .shaft wipers are raised two vertical steps in the well-known manner: The rivate magnet relay 80 and private magnet 9 are operated similarly to the first selector private magnet relay 63 'and private magnet 65, thus locking the side switch in sending of the impulses, `and releasing it to second position when the impulses have been delivered. The side switch wipers 161 and 162 now engage their second position contact points, closing the energizing circuit ofthe rotary magnet 78, whereupon the rotar magnet 78 rotates theushaft wipers 163, 164v and 165 into engagement with the bank.. contacts .of a ,trunk leading to a con#v nector switch, an idle trunk being chosen inthe same manner as previously explained for the first selector. After the Switch comes to rest with the side switch in third position the shaft wipers 163, 164 and 165 are in engfgement with the trunk conductors 166, 167 and 168, respectively, which lead tothe connector switch F. At .the instant l'that the side switch wipers 151 and 152ipass to third position, into engagement with the contact points 169 and 176, the subscribers line conductors are extended to the switch F, and an energizing` circuit is established through the line relay 86 in the same manner in which the energizing circuit was established throu'lil the `line relay 74 of the selector switch when the repeater relay 67 was first energized. The energizing circuit through the linev relay 86 extends from ound G13 through thev wmding 87 of the ine relayoytrnk line condoctors -"167 and 149, resistance rcoil 73, sprin s 71 and 70, trunk conductors 148 and 166, t rough the winding y 88 of the line relay to thebattery lead 89,1;h'ehn'aiV through batteryV B to ground G. The line relay 86, upon ener izing, operates to shift the spring 172out* o Vcontact with the spring 171 and into contact with the spring 173, whereby an energizing circuit is established through the release relay 92,V said circuit extendin from ground G1* through springs 172 an 173, release rllay 92 to the battery lead. When the relay 92 energi'zes, the s ring 174 is shifted out of engagement with e spring 175 and into engagement with the spring 176, and the spring 94`i`s shifted into engage'ment with the spring 93. The en gement of the springsl 93 and 94 establiss a energized twice,

protecting the trunk 111e conductors '166, 167 and 168 against seizure by another second selector. This kpotential extends from ound` G1? through ,contact point. 17 7, si e switch Wiper 178,

first position `during the 'ground G,

`at the springs 171 and Anet 101 is broken.`

springs 98 and`94, trunk line conductor 168- to the Vprivate p bank contacts multipled through the selector banks of this group. Furthermore, after the side switch of the second selector E passes to third position a new energizing circuit is established for the release relay 81, said circuitgextending from ground G15y through the conductor 168, shaft wiper 165, side switch wiper 162,

contact point 179,@release relay 81 tothe battery lead 89, thence through battery B to ground G. This is the condition of the connector when the subscriber operates` the dial for the last two digits. g

The third digit being 2, the impulse spring 14- is twice carried out of engagement ,with the impulse sprin 13, whereby the energizing circuit throng the repeater relay 67 is twice momentarily broken. The relay 67 deenergizes twice momentarily, and permits the springs and 71 to discngage twice, thus breaking the energizing circuit of the connector' line relay 86 twice. When the impulses are transmitted both line relays are operated over the circuits previously traced. The release relays 72 and 92, being slow-act ing, as mentioned, do not denergize during the impulses, but remain in an "operated condition. When the line relay 86 deenergizes momentarily, the spring l172 engages the spring 171 whereby an energizing circuit is completed through the vertical magnet 90, said circuit extending' from springs 172 and 171, sprin s 174 and 176, private magnet relay 100, vertlcal magnet i 0, contact -point 180, side switch wiper 181 to the' battery lead 89, thence through battery B to` ground G. The vertical magnet: 90 is thereby energized twice, and the shaft and shaft wi ers are raised two vertical steps in the well: The rivate magnet relay 100 is also in-` clude in this ener izing circuit of the vertical magnet 90. 'I ghis relay also energizes, but bein a slow acting relay it operates on' the first impulse and remains in an o erated4 position until all the impulses are de ivered.

his relay, upon energizing, operates Vto shift the spring 182 out of engagement with the spring 183 and into engagement with the spring 18 whereby an energizing cir cuit is established through the rivate magnet 101, said circuit extending From ground Gr16 through springs 182 and 184, private magnet 101 to the battery lead89. The private magnet relay course,after-the last impulse, since this energizing circuit is no longer maintained 172, Wherebythe energizing circuit through the private mag? The magnet 101 new de-w energizes, permitting the side switch wperrsl to engage their respective second position" contact points. 1.

The calling subscriber operates the,1

own manner.

magnet relay 100, springs 186 and 185,A

rotary magnet 91, contact point 187, side switch wiper 181 to the battery lead 89. The rotary magnet 91 then opera tes to rotate the shaft wipers 83, 84 and 85 into engagement with the desired line #2220. Again the private magnet relay 100 energizes, as in the previous case, remaining so until all the impulses are transmitted, thereby retaining theprivate magnet 101 also energized and the side switch in second position. 1f the line, #2220 isrbusy at the time, the connec-.tor side switch will be looked. in second posit-ion in a manner to be described., and the calling subscriber is given a busy signal, thus making it impossible to extend the call ing line into connection with the called line. Before describing the results that follow when the connector nds a busy line, the description of' how a connection is established will be completed. As soon as the line relay 86 ceases to operate for the last digit, the private magnet relay 100 denergizes, as heretofore explained, in this in stance permitting the private magnet 101 to deiinergize, allowing the side switch to pass to third position, and the side switch wipers 188, 189, 190, 178111161 18.1 toengage the contact points 191., 192, 193,194 and'195, respec tively. When the side switch wiper 190 engages the contact point 193, a. guarding potential isvextended from ground G17 through said contact point and side switch wiper, locking relay springs 196 and 197 to the private wiper 85, for protectin the seized line from outside interference W .rile the con nection is established. Not only does this guarding potential prevent other connectors from connecting with this line over multiples of the normal conductors 198, 199 and 200, but it also provides ineens for energizing the cut-off relay 201 of the line switch C', whereby said line switch C is prevented' from operating when thc called subscriber' removes his receiver 202 from. the switch hook 203.. lt will also be seen that when the side switch passes to third, position, the trunk release coinluctfin` 108 that runs between tbe'second selector E and connector l? is provided with a guarding potential 'from ground G through the line relay springs 172 and 173, Contact point 1911, sith` switch wiper 178. release relay springs 925 and. 91 to the trapte conductor 168. Of course, when the side switch wipers 188 and 189 engage their t ird position Contact points 191 and 192,y he calling subscribers line is placed in connection with the called subscribers line over the heavy conductors shown, passim-r through the ringer relay springs 204- and 205 on one side and 206 and 2,07 ou the other side. As soon as connection is thus established, the ringer relay 99 is energized over the circuit established when the side switch wiper 181 engages the contact point 195, the energizing current flowing from ground G through the interrupter 98, the back bridge relay springs 209 and 208, ringer relay 99, contact point 195, side switch wiper 181 to the battery lead 89, thence through battery B to ground G. It will be seen that as the interruptor 98 revolves, the energizing circuit of the ringer relay 99 will bebrokcn periodically, so as not to ring the called subscriber continuously. Each time that the ringer relay 99 is energized, the springs 204 and 200 are separated from the springs 205 and 207 and pressed againsgfthe springs 210 and 211, thereby breaking the calling line from the called line and cor1- netting the called line with the terminals of the ringer generator l. As a result, ringing current is sent over the called line for energizing the bell 212 while the springs 218 and 214.` are in contact.

As soon as the called subscriber answers, the back bridge relay 95 is energized by a 95 flow of current from l round (11", winding 97 of the back bridge re ay 9.5, ringer springs` 207 and 206, side switch wiper 189, Contact point 192, shaft wiper 84, normal line conductor 199, line conductor 215, primary cir- 100 cuit of the substation A2, line conductor 216, normal conductor 198, contact point 191, side switch wiper 188, ringer relay springs 204 and 205, winding 96 ot' the back bridge relay to the battery lead 819, thence through battery B to ground G. When the back bridge relay energizes, the spring 209 is shifted ont oit engagement with the spring 208, thereby breaking the ringer relay energizing circuits 1n this way the called sub 110 scriber is automatically signaled andV cuts ofi' the ringing current by answering the signal. The subscribers being thus connected may communicate over the main talking conductors indicated by the heavy lines and including the condenscrs 106 and 107 at the connector F.

lVhvn the subscribers are through talking, and if the called subscribeqhangs up his receiver first, the energizing circuit for the back bridge relay 95 is broken and the relay fleiincrgizes, closing the ringer circuit again and ringing the bell again it' the calling subscriber has not yet hung up his receiver. When the calling subscriber hangs up his receiver, the energizing circuit forithe rebrought abltlgs follows: At the instant the circuit is broken, as mentioned, the repeuter relay 67 (lcncrgizes, breaking the c1rcu1t for the release relay 72 its Well as 'for the connector line-relay 86; The con nector line lrelay SG, upon denergizing, breaks the euer izing circuit of the release relay 92 as -wel as of the release relay 8l of the second selector. Both these relays cordingly, on restoring to a normal position, close the release magnet circuits of both the selector and connector. At the connector this curcuit extends from ground G through the line relay springs 172 and 171, release relay springs 174 and 175, releaee magnet 103, off normal spring 104, contact poi-nt 105 to the battery lead 89, then e through battery B to ground G. At the si. s

.ond selector the energizing circuit extends;

of the line switch C. As soon as each shaft reaches 'its lowest positionit breaks the ener gizin g circuit `for the release magnet on that' sWitch.`Both 'the second selector and conH nector are new in 'a normal position'. The lirst selector is released similarly by u breakincr oi." the energizing circuit of its release relay. This occurs when the release relay 72 ',(its circuit being broken as mentioned) denergizes, breaking the energizing circuit for the release relay 62. The release relay 6'2 accordingly denergizes and close-s the springs 137 and ,138 into Contact, thereby closing an energizing circuit for the release magnet G6 from ground G throughsprings 135 and 134, springs 137 `and 138,1release magnet 66, contact point 60 off-normal spring 59 to the buttery lead 89,. thence through battery B to ground G. The release magnet 66 accordingly cnergizes and releases theselector switch shaft instantly, restoring the side switch to normal pos1t1on.`

W'henthe shaft reaches its lowest position thea. 61 engages the off-normal spring 55, shi tin thespring 59 out of `engagement with the c ntaet point 60, thereby breaking theenergizing circuit of the release magnet 13G. When the release rela springs 137 and 13S come into contact, as efore mentioned, another energizing circuit is closed for the release magnet 19 of the line switch (l. This circuit extends from ground G through the line relay springs 135 and 134, springs 137 and 138, releasing relay 3l, springs 219 and 220, release trunk conductor 131, release magnet 19 to the battery lead 89, thence through battery l to ground G. This ciruit includes the magnet 1,9, as above, which 1s accordingly energized, and also includes the slow-acting relay 3l, `which is also energized. But the relay ll breaks its own energizing` circuit as well as theencrgizin circuit l`or the release magnet. 19 and, eing slow-acting, does not instantly resume e. normal position. During this interval. when the relay 31` is fully operated, the re` .lease magnet 19 is denergized, and the plunger Withdrawn from the bank terminal contacts, releasing said line switch completely. 0f couree,`the release magnet cannot again energize `when' the relay 3l falls back, because the bank sprin s 23 and 2l are disengaged. When the ban. springs and 26V disengage, the bridge-cut-oli" relay() denergizes. The lirst selector and line switch are non7 completely released, and the subscribers at either substation may insrantly call again any number desired.

Returning now to that stageof the call Where the calling subscriber was operating the connector switch in accordance 'with the last digit 0, it willJoe explained what takes` lace in the event that the desired line is usy. When the line #2220 is calling, yor

-When `it has been called-,Eby someone else',

the private bank-contactsflniwhich the normal conductor QOOterminates, are connected to ground. If another connector switch has called the line this guarding potential Will be supplied from a ground terminal similar to the ground terminal G in the connector switch F, as already explained; but if the tine #2220 is calling, the line switch O` will be operated and ,the guarding potential -will he supplied from the ground Gr.21. [n

a. similar Way the -line switch C protect-stifle sur` calling line A, when the bank springs-25 and 26 come into' contact. l1`he.rel*ore',when the subscriber svendsin the last impulsethe privatewiperl 85 is carried onto a. grounded lio contact, and 'when the slow acting relay 100' denergizes, insteudof the Side switch tripping to third positiom as iu the ease where the line is not busy, it is locked, and the callin@v subscriber is then given a busy si nal.. fhe new energizing circuit for the private magnet 101, maintained during' the' i time the private magnet relay 100 is de-` f v energizing, extends from the grounded ,terminal of the batterl through en occupying switch (not shown "through the private normal conductor 200, shait wiper 85, lockt` ing relay springs 197 and 196, side switch wiper 190, Contact point 221, through the springs 2:23 and 229 of the back bridge relay 95 (this relay being now energized over n circuit which will be traced laten) through'` the private magnet 101 to the battery lead 89, amil thence through battery B to ground relay-95 to the battery lead 89.

' groun occupyingswi-tch through the private wiper,

ground G11.

Thus, when the subscriber #2220, who 'was G. The backbridge relay 95 is energized whenever the private wiper engages a grounded contact with the side switch in second position. Accordingly, the instant the busy contact is touched y the private wiper the relay 95 isV energized over a circuittrom thev grounded terminal of the battery through an occupying switch (not shown), through the private wiper'85 and to the contact point 221, as previously traced, thence through the contact point 224, side switchwiper 188, ringer sprin s 204 and 205, winding 96 of the back rid e When t e priva'te magnet relay 100 denergizes, and the spring 1-82 engages the spring 183, an energizing circuit is established for'th'e locking relay 102.A Said circuitextends vfromground G18 through springs-182 and`183,

private magnet s rings 226 and 225, locking relay 102 tothe attery lead 8 9. The relay 102,v u onenergizing, shifts the holding for' the private vmagnet from an asA previously traced, to the busy, releases his switches, and 'of course removes ythe ground potential from the private contact, the `connector, F will not trip in on this' line, 'but will continue to give the calling subscriber the busy-signal, the private magnet being still'locked.v 4When theA calling' subscriberV hangs up hisl receiver, he breaks ,the circuit-ofthe repeater relay 67 and initiates'therelease of 'all the switches, as before explained.

From the foregoing `it will the seen that I provide a repeater" for c'pntrolling the swltch or Switches that are'employed for automatically extending connection in the direction of the called'subscriber, in a system in which no operating grounds are nec` essary at the substations, a'nd in which' the supply of current for talkingA purposes is derived'from suitable means atfthe exchange or central station, rather thanroin batteries at the substations. The re eaters are convtrolled over ythe two sides o the line circuit in seriesLand the automatic 'switches are also controlled over the two sides of the line circuit in series. In other words` the circuits-'for controlling the repeaters, and the circuits controlled by the repeaters, each include the two sides of the talking circuit in series--that is to say, include portions of the two sides of the talking circuit in series. The repeaters R serve to-extend connection from two-Wire calling subscribers to twowire called subscribers, the equipment of the calling vsubscriber being identical with that of the called subscriber,

It will be seen that the selectors and connectors have vertical motion to select groups and rotary motion to then nd a line in any Iferent portion 4of' said' talkin series to entendy connection'in t e direction selected group. 'The rotary motion of the selectors is, of courseautomatic, whereby the selection of idle trunks is accomplished automatically;vv On the other hand, the rotary motion ofthe connectors is under the direct and constant control of the callingsubscriber, whereby'a particular or predetermined line in the' se ected group may be seized. Means. are provided for automatically reducing the 'numberof bridgesy across any established talking circuit. The bridge or bridges remaining across any talking circuit are .as explained,;adapted to serve as a i means. or controlling 'the trunk-release circuits over which the4 switches are releasedafter the 'subscribers are through talking,y W'at I claim Aas my invention is 1; n a telephone system, the combination 'of a talking' `circuit between4 calling and called subscribers Vhaving a section' 'normally disconnected from the calling line', an automatic switch and means for transmitting a varying numberof impulses over portions' of the 'two sides ofV said circuit 'in series'to control said switch over the two' sides of a difcircuit in of the called subscriber,.' a repeater in the f talking circuit individualto said section for controlling the said. automatic switch, said y `repeater being also; controllable over por tions of Vthe'two s1des of said circuit in series, and means at the central ,station for supplying-'current through the repeater and over portions of the said circuit to the callcontrolling the said automatic switch, said repeater being also controllable over por-I tions of the two sides of said circuit in series; and means at they central stationfor supply-- ing current through said automatic switch and over portions of the said circuit to the called subscriber for talking v u rposes.

3. Ilfa telephone systcmt e combination of a talking called-subscr1bers having a section normally disconnected from the-calling line, a11 automatic switch and means forA transmitting a varying number of im ulses over portions of the two sides of. sai circuit in series to control'said switch-over `the two sides of a dierent portion of said talking circuit in circuit between calling and 'Circui series, ond moans et the control station for suppling current over orticnsiof the said to the calling'l S11 scriberfor'ftsilking'l Purposes; l

- 4.' Inaitelephone systein,the" combination n of af talkingl ircuitlbetween: calling and celled subscribers havin' .a section normally v c disconnected fromthe ca, linlgflne, andante:

`notitie, switch and'j ineens forftransmitting a varyiizig` number lof ulsesgover portions of the two sides oi said?. circuit in'se'ries to bridged actQSa 511i the station i two sides ofthe li trolled thereby diiferejnt portion 'ciY said tzilking circuit -n seriesto extendeonnection inthe direction of the 'called siibeeribelt, repeater in the talking circuit individual to said section for ccntrollingthesid 'commotie sentori, said repeater being also controllble over portions of lthe two sidBSfof-said circuit in series, and means at the vcentrnlV staltionf for Y supplying current over portions of the `seid` circuit to the called purposes.4

5. n a 'teleph'he system, the combination of a two-wire ''cai'lili'gtelephone line, a, Suitsubscriber for able called tele lioneli'ne, means incll'iding'- a repeater an en `automi,ntic switch controllcd thereby' for cxiiefldlf connection from the 'line tllhe ed line', said repeaterinclu Ting` ej dollewund A relay batrrcnt .to `thel csllirngiine these dtwo'- r-tete "oneline being rovlded "w nscree A. Y 6. In ilI telephonesystem, the combination of :i twowire`c`ellig telephone liners), snit#A able called tele hone: lirflefmes lding en automatic switchs-conf-1A trolled thereby for extendinconnecties a; rcprenter an from the callin 'line totlie ca ed line',` sniidl repeater inclu In '7a Wound, relay:

bridged across ,suf lin nd arcoxnnion bettery for ysupplyi i y culled n line,` the two-,iticfteleiiionc n line being provided a "caHlngfnech Y 4, chisme@ thc siibstationr oricontrollin the 7. "Ina telep' ofc, suitable *calli A wire called telephone line, 'means including a repeater and an automatic switch? confrorn the callin" Ifline to tejcslled line, siii l Vrepeater inclu rig'V a doublc-wound relay bridged across scid line, and :t common but@ tery for supplyingl talking current to 'the i f 9;-111 .aictelephone system two'- "nttlie central station for supplying current' alii!! imei: epism ab.

faction 'of the called siibscribri a :repeater `.,c1irrent to the-1in the "talking circuit-fon centralini-)` befehl-59 e system, um 'combinaison telephone liricin a. two;

lfor extending connection `calling line, the said two-wire hone-line`y being rovdod with :i calling inec anism at the 'su station thereof` for controllingtho two sideso tliclinc in' series, t i

.8. In `ctc'lephonc systemgthe combination ofn suitable calling telephone lineyartwoe -wire celled telephone line, means `including el repeater and 4:infantomatica switch conl Vtrllcd thereby for extending connectiony from the callin line to the called linesaid l repefter inclut nog` s,` double- Wound relay-x bridgedlacross seid line.4 and a-lcoinmon-Ybfrt- A :telg for supplying talking current Ato the ca edrvlineftliesoid twofwire tele hone` line being rovidedwith aca-lling mec muismat ,thcvsu station thereof for controlling `thci two sidesotlie line in series. iniwhich the:4 'snb'scribers-'lines ,are divided 4into groups-yl :tenedor-establishing :i talkingjcircuit rbe;

prising n. talking circuit section corninonto Volli"the linesiof o group, :innutomnticp switch, means for transmitting avarying@ number .of impulses over portions offihe@ saidswtch over thc two sides of e dition.-

` ent .portion of scid talking circuit inseries.,4

tovextend connection in the .direct-ion'oftheLA 4tween Vcolling and called slibscribers,iecoiiff35 '51V' ytwisiftlest of said circuit in series to control 90 celled subscriber, :Lrepe'ater in theV talkin "if if being slso'controllable over portions ofthe ""'oles oflsail' circuit in series,l andmeens through the repeater :indover portions-of itliegsnid: circuit toltlie calling subscriber for circuitindifidua'l to scid section for contro .o5v

ling thcscid automatic switcln said repeater l talkingpurposesfseid automatic switch have in'g'v first orie'wi'notion to select a group and 'tiiennl second niotion to find thc cailledwl-ne inltlie predetermined vgroup.

10.77111 n telephone system Vthe combination olin talking circuit rlcet'iireen,

ir. ,105 I infrvl-iichy the. i subscribers* lines are Vdnnded into-v groups,

callingnd'*celled-subscribersen automatic' switch` and mea-ns .for transmitting' ai varysf saidfSWitlf tojext/endv connection nwih seidI 'automatic switch,- *sei repeater. sing 1 also "controllable ,mier portions ofrrthe two' sides of said'circuitl in series, ,and ineens et4 the *control station Afor supplyin-gfcurrent g inglnlimbcr ofwimpulses oyer portions oitle two sides ofi sind circuiti-1n senos to control through seid automatic 'switchniid over por@ 120 tionsfof ,the seid circuit to Ashe; celedy sul.` i

4scuri-ber Afor` tolltingpurposes, scid {tutomatic switch having firstverticnl motionjto select a 'roup and thenrotcry motion to 'find thel ca leil 'ine ,Jin the, predetermined group.

l1. In n telephone system in ywhich the subscribers lines `are divided into groups, the combination of atalking circuit between calling and called subscribers, an automatic switch land means for transmitting a varyfing number of impulses over the two sides 'of a Vportion of said circuit in series to control said'switch over the two sides of a different portion of said talking circuit in -series'to extend connection in the direction of the called subscriber, a repeater in the talking circuit for controllin the said autotral'staationfor supplyingcurrent over portions'ofthe said circuit to the calling subscribe'rfor' talking purposes, said automatic switch having first vertical motion to select ya grou' and then rotary motion to find the @33h led ine in the vpredetermined grou 12.1111v a telephone s stem in whic the subscribers :lines are ivided into groups, the combination of a talking circuit between calling 'and called subscriberasn automatic switch and meansfor transmitting a varying number of limpulses over V portions of the two sides of said: circuit lin series to control said'rs'witch over the two sides of a diii'erent portion of said talking circuit inseries to extend connection in the direction of the called subscriber, a repeatery in the talking circuit for controllingthe said automatic switch,l said repeater lbeing also controllable over portions of the two sides of said circuit in series, and means at the central station for supplyingcu-rrent over. portions ofthe said circuit to the called subscriber for talking purposes, said automatic switch having lirst vertical motion to select a group and then rotary motion to findv the called line in the predeterminedgroup.

1,3. In a telephone system in which the subscribers lines are divided into groups, the combination of a .suitable calling telcphone line, a two-wire called telephone line, means includ-in a repeater and an automatic switch control ed thereby for extending a talking circuit from .the'calling line to the called line, and a 'common battery for supplying talking current to the calling line, the said callin telephone line beiiig provided with a ca ling mechanism at the substation thereof for transmitting a varying number of impulses over the two sides of a portion of said talking circuit in series to control said switch over the two sides of a dierent ortion of said talking circuit in series,.sa1tl automatic switch having first vertical motion to select a roup and then rotary motion to lind the ca led line in the 'predetermined group.

14. In a telephone system in which the subscribers lines are divided into groups,

l`the combination of a suitable calling telephone line, a two-wire called telephone line,

means including a 're eater and an automatic switch controlle thereby for extendpredetermined series, said automatic switch havingr first vertical motion to select a group an then rotary motion to lind the called line in the predetermined roup.

15. In Ia telep one exchange trunkin 'system in which the trunk lines are divide* into roups, the combination of a talking circuit I etween calling and called subscribers, an

automatic switch and means for transmitting a Vvarying number ol' impulses over portions of thetwo sides of said circuit in series to control said switch over the two sides of a different portion of said talking circuit in-series, to extend connection in. the direction of the called subscriber, a repeater in the talking circuit for controlling 'the said automatic switch, said repeater being also controllable over portions o the two sides of said circuit in series, and means at theA central station for 'supplying current through the repeater and over portions of the said circuit to the calling subscriber for talking purposes, said automatic switch havin first vertical motion to select a group an then rotary motion to automatically select an idle trunk in the predetermined. group.

16. In a telephone exchange trunlring System in which the trunk lines are divided into groups, theiconibination of a talking circuit between calling andcalled subscri ers, an automatic switch and means for transmitting a varying number of impnlses'over portions of the two sides of said talking circuit in series to control said switch over the two sides of a different portion of said talking circuit in series to extend connection in the direction of 4the called subscriber, awrepeater in the talking circuit for controlling"tli`e.aaid automatic switch, said repeater being also controllable over portions of the two sides of said circuit infseries, and means at the central station for supplying current overl portions of the said circuitA to the calling subscriber .for talking purposes, said automatic switch having first vertical motion to select a group and then rotary motion to automatically'sclect an. idle trunk in the cup. y

17. In a telep one exchange trunkin system in which the trunk lines are divide. into groups, the combination of a talkin clrcuit between calling and called subscri ers, an

automatic'switch and-means for transmitting a varying' number of impulses over portions of the two sides of said talking circuit in series to control said switch over the two sides of a dilferent portion of said talking circuit in series toextend connection in the direction of the called subscriber, a repeater in the talking circuit for controlling the said automatic switch, said repeater be ing also controllable over portions of the two sides of said circuit in series, and means at the. central station for supplying current over portions of the said circuit to the called subscriber for talking purposes, said automatic switch having iirstvertical motion to select a group and then rotary motion to automatically select 4an idlc trunk in the predetermined roup.

18. In a telep one exchange trunking system in which the trunk lilies are `divided into groups, the combination of a twowire calling telephone line, a suitable called telephone line, means including a re eater and an automatic switch controlled t ereby for extcndin f a talkin circuit from the calling line to te called line, and a common battery for sup lying talking current to the calling line, tlie said two-wire telephone line being rovided with a calling mechanism at the su station vthereof vfor transmitting a varying number of impulses over the two sides of a portion of said talking circuit in series to control said switch over the two sides of a diEerent Jorton of said'talking circuit in series, saidl automatic lswitch having first vertical motion to select a roup and then rotary motion to automatically select an idle trunk in the predetermined group.

19. In a telephone exchange trunking s stem in which the trunk lines are 'divi ed into groups, the combination of a two-wire calling telephone line, a suitable called telephone line, means including a repeater and an automatic switch controlled thereby for extendin a talking circuit from the calling line to t .e called line, land a `comnion battery for supplying talking current to the called line, the said two-wire telephone line being rovided with a calling mechanism at the su `station thereof for transmitting' a varying number of impulses over the two sides of a portion of said talking circuit in series to controlsaid switch over the two sides of a different portion. of said talking circuit in series, said automatic switch having first vertical motion to select a group and then rotary motion toautoxnetically select an idle t'runk in the predetermined group.

20. In a telephone exchange trunking system in which the trunk lines are divided into groups, the combination of a suitable calling telephone line, a two-wire calledtelephone line, means including a repeater and an automatic switch controlled thereby4 for extending a talking circuit from thecalling line to'the called line.and -a common battery for supplying talking current to the calling line, the said calling telephone line being provided with a calling mechanism at the substation thereof for transmitting a. varying number of impulses over the two sides of a portion of said talking circuit in series; to control said switch over the two sides of a different portion of said talking circuit inseries, said automatic switch having first vertical motion to select a group and then rotary motion to automatically select an idle trunk in the vpredetermined group.

21. In a'telephone exchange trunkng system in which the trunk vlines are divided into groups, the combination of a suitable calling telephone line, a two-wire called telephone line, means includ a re eater and an automatic switch contro led t ereby for extending atalking circuit from the calling line to the calledline, and a common battery for supplying talking current to the called line, the said callin telephone line being provided with a cal Ving mechanism at the substation thereof for transmitting a varying number of impulses over the two sides of "a portion of'said talking circuit in series to control said switch over the two sides of a different portion of said talking Circuit in series, said automatic switch havin first vertical motion to select a group an then rotary motion to automatically select an idle trunk in the predetermined group.

22. vIn a telephone system employing relay bridges acrossthe conductors of the talking circuit for controlling automatic switches, the combination of a talking circuit between calling and called subscribers, said talking circuit havin a section normally discon- -nected from t e subscribers lines, an automatic switch controllable over portions of the two sides of said circuit in series, to extend connection in the direction of the called subscriber, a repeater in the talking circuit individual to said section for controlling the said automatic switch, said repeater being controllable over different portions of the two sides of said circuit in series, means at the central 4station for 'supplying current through the repeater and over portions 4of the said circuit to the calling subscriber for talking purposes, and vmeans for automatically reducing the number of bridges across the conductors of any talking circuit during" the establishment thereof.

23.y In a telephone system employing relay bridges across the conductors of the talking circuit for controlling automatic switches, the combination of a talking circuit between calling and called subscribers. said talking circuit having a section normally disconnected from the subscribers` lines, an automatic switch controllable over portionsof the two sides of said-circuit in series, to extend connection in the direction of the called subscriber, a repeater in thetalking circuit individual to said section for conlim.'

trollingJ the said automatic switch, said repeater eing controllable over different p ortions of the two sides of said circuit in series,

means at the central station for supplyingcurrent through said automat-ic switch and over portions' of the said circuit to the called subscriber for talkin purposes, and means for automatically re icing vthe number of bridges across the conductors of any talking circuit Vduring the establishment thereof.

24. In a telephone system employinfg rebridges across the conductors o the ta king. circuit for controlling automatic switches, the combination of a talking circuit between calling and called subscribers, said talking circuit having a section norinally disconnected from the subscribers lines', an automatic switch controllable over portions ofthe two sides of said circuit in series, 4to extend connection in the direction of the called subscriber, a repeater in the talki circuit individual to said section for contro lin the said automatic switch, said repeater ge portions of the two sides of said circuit in series, means at the central station for supplying current over portions of the said circuitjto the Vcalling subscriber for talking urposes, and means for automatically reducing the number of bridges across the conductors of any talking circuit during a,- tablishment thereof.

25. In a telephone system employing rela bridges across the conductors o the talking circuit for controlling automatic switches, the combination of a talkin ciru cuit between calling Vand called subscribers, said talking circuit having a section nor- `mally disconnected from the subscribers lilies, an automatic switch controllable `over portions vof the two sides of said circuit in series, to extend 'connection in the direction of the called subscriber, a repeater in the talki v circuit individual to .said section for contro lin the said automatic'switch, said repeater being controllable over di'ereiit portions of the twosides of said circuit in series, means at the central station for supplying current over 4portions of the said 'circuit to the called subscriber foi-'talking ur'poses, and means for automatically reucing the number of bridges across the conductors of any talking circuit during the establishment thereof.

26; In a telephone system employin re-I la bridges across the conductors o the `talking circuit for controlling automatic switches, the combination of subscribers lines which are free from operating grounds outside of the exchange or centralstation, trunk linesI provided with repeaters, means controllable'over said subicribers lines for automatically selectin idle repeaters, alitomaticlswitches contro lable by said repeating controllable over different ers, means at the exchange or central station for supplying talking current to callin subscribers, and means for automatica y reducing the number of bridges across the conductors of any talking circuit during the establishment thereof.

27. In a telephone system einployin rclay bridges across the conductors o the talking circuit for controlling automatic switches, the combination of subscribers lines which are free from operating grounds outside of the exchange or central station, trunk lines provided with re eaters, means controllable over said subscri ers lines lfor automatically selecting idle repeaters, auto matic switches controllable by said repeaters, nieansat the exchange or central station for supplyin talking current to called subscribers, an means for automatically reducing themuinber of bridges across the conductors of any talking circuit'during the establishment thereof.

28. In a telephone system employin rela bridges across' the conductors cig the ta king circuit for controlling automatic s'witches, the combination of subscribers lines which are free from operatin grounds outside of the exchange or centra station, trunk lines provided with repeaters, means controllable oversaid subscribers lines for automatically selecting idle repeaters, automatic switches controllable by said repeaters, means at the exchange or central staltion for supplying talking current to both calling and called subscribers, and means for automatically reducing the number of bridges across the conductors of any talking circuit durin the establishment thereof.

29. In a te ephone system employin rela bridges across the conductors og the ta kingcircuit for controlling automatic switches, said talking circuit havin a secics tion normally disconnected from t e subscribers lines, the combination of a two wire callin telephone line, a suitable called telephone ine, means including a repeater' individual to said section controlled over two sides of a portion of said talking circuit in series and an automatic switch controlled thereby over two sides`of a different portion Vof said talking circuit in series for extendin connection from the calling line to the ca ed line, a common battery for supplying talking current to the calling line, the said two-wire telephone line being pro vided with a calling mechanism at the substation thereof for controlling the two sides of the line inseries, and means for automatically reducing the number of bridges across the conductors of an talking circuitl during the establishment t ereof.'

30. In a telephone system employing rela .bridgesacross the conductors "o ',ftlie4 ta king controlling IIE switches, said bridges including a battery connected in series therein, the combination of a two-wire calling telephone line, a suitable called telephone line, means including a repeater and an automatic switch controlled thereby for extending connection from the calling line to the called line, a `common battery for supplying talking cur rent to the called line, the said two-wire4 telephone line being provided with a calling mechanism at the substation thereof for controlling the two sides of the line in series, and means for automatically reducing the number of bridges across the conductors oi. any talking circuit during the establishment thereof.

31. In a telephone system employing relay bridges across the conductors of the rent to the calling line, the said calling telcphone line being provided with` a calling mechanism. at the substation thereof for controlling the two sides of the line in series, and meansY for automatically7 reducing the number of bridges across the conductors of any talking circuit during the establishment thereof.

32. .In a telephone system employing relay l bridges across the conductors of the talking circuit tor controlling automatic switches, said bridges including a battery connected inseries therein, tbe combination of a suitable calling telephone line, a two-wire called telephone line, means including a repeater and` an automatic'switch controlled thereby for extending connect-ion from the calling line to the called line, a common battery for supplyingwtalking current to the called line, the saidcallng telephone line being provided with a calling mechanism at the substation thereof for controlling the' two sides of the line in series, and means for automatically `reducing the number of bridges across the conductors of any talking circuit during the establishment thereof.

33. In a telephone system employing .means for automatically disconnecting or cutting oil' an automatic switch from thev conductors of the talking circuit, the combination of a talking circuit between calling and called subscribers, said talking circuit having a section normally disconnected from the subscribers lines, an automatic switch controllable over portions of the two sides ofsad' talking circuit in series, to extend connectionyin the direction of the called subscriber, a repeater in the talking circuit individual to said section for controlling the said automatic switch, said repeater being controllable over diil'erent portions of the two sides of said circuit in series, means at 'the central station for supplying current through the repeater and over portions of the said circuit to the' calling subscriber for talking purposes, and trunk-circuit-controlled releasing means for restoring the switch disconnected from the conductors of any talking circuit.

34. In a telephone system employing means for automatically disconnecting or cutting olf conductors of the talking circuit,` the combination of a talking circuit between calling and called subscribers, said talking circuit having a section normally disconnected from the subscribers lines, an automatic switch controllable over portions of the two sides of said talking circuit in series, to extend connection in the direction of the called subscriber, a repeater in the talking circuit indi'idual to said section for controlling the said automatic switch, said repeater being controllable over different portions of the two sides of said circuit in series, means at the central station for supplying current over portions of the said circuit to the calling rsubscriber for talking purposes, and trunk-circuitcontrolled releasing means for restoring the switch disconnected from the conductors of any talking circuit.

35. In a telephone system employing means for automatically disconnecting or 'cutting oil' an automatic switch from the conductors of the talking circuit, the combination of a talking circuit between calling and called subscribers, said talking circuit having a section normally disconnected from the subscribers lines, an automatic switch controllable over portions of the two sides of said talking circuit in series, to extend connection in the direction of the called subscriber, a repeater in the talking circuit individual to said section for controlling the said automatic switch, said repeater being controllable over different portions of the two sides of said circuit in series, means at the central. station for supplying current over portions of the said circuit to the called subscriber for talkingpurposes, and trunk* circuit-controlled releasing means for restoring the switch disconnected from the conductors of any talking circuit.

36. In' a telephone system employing means for automatically disconnecting or cutting oil an automatic switch from the conductors of the talking circuit, the combination of subscribers lines which are free from operating grounds outside of the excliaige orv central station, ltrunk lilies provid with. repeaters, .controllable an' automatic switch from the over said subscribers lines for automatically selecting idle repeaters, automatic switches controllable by said repeaters, means at the` exchange or central station for supplying talking current to calling subscribers, and i'ruiik-circuit-vcontrolled releasing means for watering the switch disconnected from the conductors oi any talking circuit.

37. lI nI 'la telephone system employing means for' automatically disconnecting orV cutting 0Hy an automatic switch from the conductors of the talking circuit, the combination of subscribers lines which are free fromA operating grounds` outside of the exchange or central station, trunk lines provided with repeaters,' means controllable over said subscribers lines for automatically' selecting id lc repeaters, automatic switches controllable by said repeaters, means at the exchange or central station for supplyin talking current to called subscriber-span trunlccircuitcontrolled releasing means for restoring the switch disconnected from the conductors of any talking circuit.

38. In a telephone system employing means for automatically disconnecting or cutting oil' an automatic switch from the conductors of the talking circuit, the combination of subscribers lines which are free from operating grounds outside of the exchange or central station, trunk lines provided with repeaters, means controllable over said subscribers lines for automatically ,selectin idle re eaters automatic switches controllable by said repeaters, means at the exchange or central station for su plying talking current ,to both calling and) called subscribers, and trunk-circuitcontrolled releasing means for restoring the switch disconnected from the conductors of any talking circuit.

39. In a telephone system employing means for automatically disconnecting or cutting off an automatic switch from the conductors `of the talking circuit, the combination of a two--wire calling telephone line, a suitable called telephone line, means including a repeater and an automatic switch controlled thereby for extending connection trom the calling line to the called line, said repeater includincr a double-wound relay bridged across sai( line, a common battery for su plyin f talking current to the calling line, t e sai two-wire telephone line being provided with a calling mechanism at the substation thereof for controlling the two sides of the line in series, and trunk-circuitcontrolled releasing means 'for restoring the switchdisconnected from the conductors of any talking circuit.

40. In a telephone system employing means for automatically disconnecting or cutting. oli` an automatic switch from the conductors of the talking circuit, the com,

bination of a two-wire calling telephone line,

A'means for automatically a suitable called telephone line, means in cludin a repeater and an automatic switch contro led thereby for extending connection from the callin line to the called line, said repeater inclu in a dcuble-wound relay bridged across sai line, a common battery for supplying talking current to the called line, the said two-wire telephone line being provided with a calling mechanism at the substation thereof for controlling the two sides of the line in series, and trunk-circuitcontrolled releasin means for restoring the switch disconnecte from the conductors of anytalking circuit. t

41. In a telephone system employing means for automaticall disconnecting or cutting oli an automatic switch from the conductors of the talking circuit, the combination of asuitable calling telephone line, a two-Wire called telephone line, means including a 'repbater and an automatic switch controlled thereb for extending connection from the callin repeater inclu ing a double-wound relay bridged across said line, a common battery for supplyin talking current to the calling line,V the sai calling telephone line being provided with a calling mechanism at the substation thereof for controlling the two sides of the line in series, and trunk-circuitcontrolled releasing means for restoring the4 switch disconnecte from'the conductors of any talking circuit. t

42. In a telephone system employing disconnecting or cutting oil an automatic switch from the conductors of the talkin circuit, the combinationof a suitable cal ingtel'ephone line, a two-wire called tele hone line, means including a repeater and) an automatic switch controlled thereby for extending connection from the callin line to the called line, said repeater inclu ing a. double-wound relay bridged across said VAline, a common battery for su plying talkingv current to the called line, t e said callin telephone line being provided with a cal ing mechanism at the substation thereof for controlling the two sides of the line in series, and trunk-circuitcontrolled releasin means for restoring the switch disconnecte from the conductors of any talking circuit.

43.111 a telephone system the combination of a two-wire calling te ephone' line, a two-wire called telephone line, means including a repeater and an automatic switch controlled thereby for extending connection from the callin line to the called line, said repeater inclu ing a double-wound relay bridged across said line, and centralized 4means for supplying current to said lines nism at the substationthereof for controlling the two sides of the line in serie,`

44. In a teleph e system. a repeater and au automatic switch controlled thereby, said repeater provided with a line relay having two windings,'a battery prnnected in series between said windings, a trunk line across which the said windings and battery are permanently bridged, automatic means for seizing said trunk line, a ground-controlling relay for said repeater, a trunk-release rir cuit for said automatic means controlled by said grouildcruitlfolling relay, said ground controlling relay having an energizing circuit controlled by energizing circuit remains closed during conversation. whereby said trluik-release circuit also remains closed during conversation` and. release mechanism responsive to the opening of said trunkaelease circuit by the said grou!lil-contrillling relay.

In a telephone system. a. trunk a repeater in said trunk pulses o\ i-r the saine, a pair of condensers in oppo ite rides of said trunk, a bridge in sail repeater arrose said trunk on one side of `said eondeusera, a double-wound relay in said bridge, and a second bridge containing an electromagnetic element across said trunk on the opposite sides of said condcnsers con trollcd by said do|xble-\\'ou1nl relay.

46. In 'a telephone system, a subscribers line. a trunk line, means including an automatic Snitch controllable over two sides of .said sub s .iil)e1`s` line in cries for extending a connection from said liuc to said trunk. a repeater in said truuk. a bridge in said re pealer across lsaid truuk, a doublt-wound relay in said bridge. and a, second bridge containing anelectroulagnetic element across said trunk controlled by said double-wound relay.

177. flu a telephone system, a subscribcfs line, a trunk line, means including an automatic switch controllable over two sides of said subscribcrs linefin series for extending a connection from said line to said trunk, a repeater in Said trunk` a bridge insaid repeater across said trunk. a. double-wound relay in said l'nidgc, a second bridge containing an electromagnetic element across said truuk controlled by said double-wound relay, and a slow acting relay in said repeater. controlled by said double-wound relay for controlling the release circuit for said automatic switch.

line,

the said line relay. which for repeating imf ksender aswclatell 48. In a telephone system, a Subscribers line a trunk line, means including an auto* matic switch l'or extending a connection 'roni said suhaeribefa line to said trunk, a pair ot' comlensers in opposite 4sides of said truuk, a bridge` in said repeater across said trank on one eide of said condensers, a doubleu-uuid relay in said bridge, a second bridge containing an electromagnetic element aeroA said trunk on opposite sides of said rondensersy controlled by said doublewound relay. a slow acting relay in said repeater controlled by .said doublewound relay, and a release. circuit Jf'or said automatic .switch roulrolled by said slow acting' relay.

ll). In a telephone system, a calling line, a called line. a link circuit for connecting the two over a talking circuit. an automatic progressively nnnable switch controlling said circuit aud operated over two sides of a portion ol `aid circuit in series. au impulse with the calling line, an impuls-e repeater inlerposed between said li|nI and said `-wi|eh. said repeater individual to said link and responsive to impulses from said sender over two sides of a different portion ol' the talking circuit in series, said repeater controlling said switch in respouse to said impulses, and a central battery for supplying rurrent for talking purposes to the. talking circuit. y

50. In a telephone'system` a calling line, a called line, a link circuit for connecting the two over a talking-circuit, an automatic progressively movable switch controlling said circuit and operated ore; the tWO sides of a portion of said circuit in series, an impulse `euder assmialed with the calling line, au impulse repeater interposed between said liuc and said switch. said repeater individual to said link and responsive to impulses from `said sender over two sides of a different portion ot' the talking circuit in series1 said repeater controlling said switch in response to sa id impulses. a cent-ral battery for supplying current for talking purposes ilto the talking circuit. said repeater normally disconnected from the calling line.

Signed by ine at Chicago, Cook county Illinois` this 2nd day of July 1909.

TALBOT ci. MARTIN. Witnesses Vl'lnwam) D. F ALES, J. Neuer. 

